package tcp

import (
	"context"

	"spark-server/internal/pkg/errs"
	"spark-server/internal/transport/tcp/protocol"
	"spark-server/internal/transport/tcp/session"
)

// CommandHandler runs in TaskPool for AUTH/SEND/SYNC and other business commands.
type CommandHandler func(ctx context.Context, conn *session.Conn, frame protocol.Frame) (*protocol.Frame, error)

// Router maps Frame.Command to a handler.
type Router struct {
	handlers map[uint16]CommandHandler
}

// NewRouter creates an empty command table.
func NewRouter() *Router {
	return &Router{handlers: make(map[uint16]CommandHandler)}
}

// Register binds a command to a TaskPool handler.
func (r *Router) Register(cmd uint16, h CommandHandler) {
	r.handlers[cmd] = h
}

// Dispatch looks up and runs the handler. Unknown commands are invalid.
func (r *Router) Dispatch(ctx context.Context, conn *session.Conn, frame protocol.Frame) (*protocol.Frame, error) {
	h, ok := r.handlers[frame.Command]
	if !ok {
		return nil, errs.ErrInvalidArgument
	}
	return h(ctx, conn, frame)
}